Abstract. The austral westerlies strongly influence precipitation
and ocean circulation in the southern temperate zone, with important
consequences for cultures and ecosystems. Global climate models anticipate
poleward retreat of the austral westerlies with future warming, but the
available paleoclimate records that might test these models have been
limited to South America and New Zealand, are not fully consistent with each
other and may be complicated by influences from other climatic factors.
Here we present the first high-resolution diatom and sedimentological
records from the winter rainfall region of South Africa, representing
precipitation in the equatorward margin of the westerly wind belt during the
last 1400 yr. Inferred rainfall was relatively high ∼1400–1200 cal yr BP,
decreased until ∼950 cal yr BP, and rose notably through the
Little Ice Age with pulses centred on ∼600, 530, 470, 330, 200, 90,
and 20 cal yr BP. Synchronous fluctuations in Antarctic ice core chemistry
strongly suggest that these variations were linked to changes in the
westerlies. Equatorward drift of the westerlies during the wet periods may
have influenced Atlantic meridional overturning circulation by restricting
marine flow around the tip of Africa. Apparent inconsistencies among some
aspects of records from South America, New Zealand and South Africa warn
against the simplistic application of single records to the Southern
Hemisphere as a whole. Nonetheless, these findings in general do support
model projections of increasing aridity in the austral winter rainfall zones
with future warming.